An embodiment of a system as is set forth in the opening paragraph is known from US2006/0025664. In the known system a rectangular waveguide is used to transmit a suitable RF signal to a body under investigation.
It is a disadvantage of the known system that a large size of a waveguide, a limited frequency band and an inferior impedance match cause substantially high reflections in the skin of the human or animal body which deteriorates accuracy of the collected data. In addition, the known system is not suitable for detecting small variations in the dielectric constant of the human or animal body (for example, due to local changes of a glucose level in blood flow).
A further embodiment of the system as is set forth in the opening paragraph is known from U.S. Pat. No. 6,463,336. In the known system an antenna used for irradiating a portion of a skin of a patient may be configurable to conform to an external shape of the body. Although this may at least partially solve a problem of impedance matching between the hardware used for irradiating and the body, the device known from U.S. Pat. No. 6,463,336 is not suitable for blood glucose concentration measurements due to a limited frequency bandwidth of the known system and a large aperture size.